1. Field of the Invention
The present invention relates to a V-belt stretching mechanism. This invention may be employed to stretch the alternator V-belt in an internal combustion engine to a specified tension. The term "V-belt" may include a belt used in an internal combustion engine whose section is different from V-shape.
2. Description of the Prior Art
With the conventional alternator in an internal combustion engine, as illustrated in FIG. 22, the rotation of crank pulley 1 is transmitted to alternator pulley 3 through V-belt 5 wound around alternator pulley 3 of alternator 2 and water pump pulley 4. For alternator 2 and the water pump to function normally, V-belt 5 should be maintained at an adequate tension.
As enlarged in FIGS. 23 and 24, the top of conventional alternator 2 is supported by bracket 6. The bottom of alternator 2 is fastened by alternator stay 7, which extends downward from alternator 2. Stay 7 cooperates with slider 8 and adjust bar 9, which is fixed to the engine cylinder block, to hold alternator 2 in place. The tension of V-belt 5 is adjusted by loosing lock bolt 10 and therefore slider 8 which has been fastened together with alternator stay 7 to adjust bar 9 and changing the support angle of alternator 2 by rotating adjust bolt 11 which is screw-engaged with slider 8.
However, this tension adjustment of the V-belt takes much time, because the V-belt has to be stretched using a tension gauge so that a specified tension can be attained. When the adjust bolt is not adequately tightened and the resulting V-belt tension is low, the V-belt itself will slip in the pulley groove, causing a squeak of the belt. On the other hand, when the tension is excessively high, the durability of the water pump pulley shaft and the crankshaft pulley shaft will drop and the belt itself will deteriorate.